Boeing Investigating Disc Rotor

The Defense Advanced Research Projects Agency (Darpa) is giving Boeing $9 million over the next two years to investigate the feasibility of developing a disc-rotor compound helicopter capable of achieving forward speeds of up to 400 ktas while retaining all the maneuverability of a traditional helicopter. The disc-rotor would have a rotating circular wing with retractable blades that extend from the disc edge for takeoff and landing. The idea for the disc-rotor was first fielded in the 1960s and patents for the concept have already been issued.